Production of metal strip



June 1, 1965 c; LUDBROOK ETAL 3,135,201

PRODUCTION OF METAL STRIP 3 Sheets-Sheet 1 Filed June 21, 1961 INVENTQRS Lasua G. LUDBROOK RAYMOND B. SIMS June 1965 c. LUDBROOK ETAL 3,135,201

PRODUCTION OF METAL STRIP Filed June 21, 1961 s Sheets-Sheet 2 W315 NTQQ 5 Lzsua C. LUDBROOK BYRAYMOND B. Sms

JA A 7%;

ATTORNEY June 1, 1965 Filed June 21, 1961 L. C. LU DBROOK ETAL 3,186,201

PRODUCTION OF METAL STRIP 3 Sheets-Sheet 3 LESLJE O. LUDBROOK RAYMOND B. Sms

ATTORNEY United States Patent 3,186,201 PRODUCTION OF METAL STRIP Leslie Carter Ludbroolr, Bilton, Rugby, and Raymond Bernard Sims, Shefiield, Yorkshire, England, assignors to Steelworks Automation Limited, a British corporation Filed June 21, 1961, Ser. No. 118,548 19 Claims. (Cl. 729) This invention relates to the production of metal strip and is particularly concerned with the control of a tandem mill, such as a continuous hot strip finishing train.

In a hot mill, a slab, the thickness of which is about 3 to inches, is rolled down to a bar in a series o roughing mills, or in a number of passes in a reversing mill, and the resultant bar, usually about to 1 /2 inches thick, is then rolled down to strip in a train of finishing stands placed close together. The setting up of the finishing stands is a complicated procedure in that the various adjustable factors of the trainthe screwdown on the various stands, the speeds of the stands and the interstand tensionsare inter-related, so that the adjustment of any factor must usually be accompanied by adjustments in other factors. In addition, the control of the finishing train to produce a particular thickness of strip is dependent on the nature of the metal being rolled, and the parameters of the bar. Lastly, the draft taken on each stand of the train is limited by the need to keep th shape of the strip satisfactory and to avoid overloading the motors on each of the finishing stands.

Because of these diificulties, it is usual to set up the train for a bar of average dimensions and properties, although the bars entering the train may vary considerably therefrom. For this reason, it is not normally possible to predetermine the nominal thickness of the strip leaving the train, although this is clearly desirable. On the other hand, the finishing train may be controlled to ensure that the thickness of the strip is constant within required tolerances, for example by use of an automatic control system such as those described in British patent specifications Nos. 681,373 and 692,267.

'In this invention, the mill is initially adjusted by the operators for the next bar to be rolled assuming that the bar is of required dimensions and temperature, and computing means, operated by measurements of the bar taken on the delay table, is arranged to adjust the mill for departures of measured parameters from the assumed values. Thus, the invention consists broadly in an automatic control system for a multi-stand train of a rolling mill comprising manually operable means for adjusting the roll setting and/ or roll speed of each of the stands, whereby an operator may set the rolls according to the desired outgoing strip thickness and according to parameters assumed for the bar about to enter the train, means for automatically measuring parameters of the bar on the delay table prior to entry to the mill, a computing circuit responsive to the diiferences between the measured parameters and the assumed parameters, and means controlled by the computing circuit for automatically altering the roll settings and/ or speeds appropriately for those differences.

The invention will be more readily understood by way of example from the following description of a system for adjusting the roll settings of the stands of a finishing train, reference being made to the accompanying drawings, in which:

FIGURE \1 illustrates schematically the mill and the control circuits;

FIGURE 2 is a circuit diagram of the computer used in the control circuit; and

FIGURE 3 shows the control of the screwdown setting of a single stand, the control circuits for the other stands being similar.

3,1863% Patented June 1, 1965 Referring to FIGURE 1, a continuous mill is shown as having a train of roughing stands 12, of which only the last stand is shown at 13. In a semi-continuous mill, a single reversing roughing stand may be used in place of the train '12. There is also a finishing train 14 having six stands I I-F6. The bar leaving the roughing train 12 1s received by a delay table 15, where it is held prio to entry to the finishing train 14.

The screwdown settings and speeds of the stands F1-- F6 are selected by the operators prior to the entry of the bar to the first stand F1, by changing those settings and speeds by amounts dependent on the differences between the thickness and width of the bar last rolled and the corresponding values required of the bar to be rolled, the hardness of the metal being rolled, and the temperature of the bar prior to entry to the finishing train 14. In practice, the bar is held on the delay table for a time sufficient to permit it to coolto a temperature in a given range. On the other hand, the temperature of the bar entering the finishing train 14 may vary by as much as C. Similarly, the width of the bar on the delay table may vary, depending on the width of strip required from the finishing mill and the variations in Width which occur due to the previous rolling processes. On the other hand, the thicknesses of bars on the delay table do not vary within a wide range, being usually about 1 inch thick and changes in this dimension do not produce large changes in finished thickness, as do variations in width and temperature. Screwdown settings and roll speeds of the finishing train are selected by the operators for the required outgoing strip thickness, on the assumption that the temperature, width and thickness of the leading end of the bar have given values, which may differ appreciably from the actual values of the bar. Having thus been selected, the screwdown settings and roll speeds of stands Fl-F6 are automatically adjusted in accordance with measurements taken automatically on the delay table of the width and temperature of the bar immediately prior to entry to the finishing train 14- and in accordance with the thickness of the leading end of the bar, measured as the bar leaves the roughing stand 13. After entry of the bar into the finishing train 14, one or more of the stands of thattrain is or are automatically controlled to maintain the outgoing thickness from stand F6 within a desired tolerance. The temperature and width of the bar on the delay table are respectively measured by a pyrometer 16 and a Width meter 17 located adjacent the first stand F1 of the finishing train. The pyrometer 16 an the width meter 17 may be of any known form, capable of giving continuous indications of the temperature and width of the bar. However, it is preferred to employ, for the width meter 17, the device described in British patent specification No. 795,525, since that device is capable of giving an indication of the departure of the width from a nominal value. The thickness of the bar is measured by a thickness detector 18 located at the exit end of the roughing train 12. This detector may also be of any known form, but is preferably a gauge .meter as described in British patent specification No. 713,105. The thickness detector 18 is effective to measure the thickness of the leading end of the bar and that thickness is stored in a store 20. Alternatively, the thickness detector may be an X-ray gauge located adjacent the width meter 17 at the end of the delay table 15.

The values of temperature, Width and thickness from the devices 16, 17, 20 are applied to a screwdown computing circuit 21 which emits on line 22 electric signals representing the adjustments in screwdown to be made to the various stands F1436 owing to the departures of these values from the values assumed by the operators in initially selecting the screwdown setting for the finishing train. The line 21 in fact represents a group of lines individually connected to setting control circuits C1-C6 for the respective stands.

vIn addition to the screwdown computing circuit 21, there is a roll speed computing circuit 19 which gives an output on line P electric signals representing the adjustments to be made to the roll speeds of the various stands -F1-F6, again required due to the departures of temperature, width and thickness from the values assumed by the operators in initially selecting the stand speeds for the bar. The roll speed computing circuit 19 is controlled by temperature, width and thickness devices 16, 17, 20, by the output from computing circuit 21, since changes in screwdown settings affect the stand speeds, and by the existing roll speeds of stands Fl-F6 as measured by tachometers T l-T6. The signals from the computing circuit 19 are applied to speed control circuits Ml-M6 for the respective stands. Circuits Ml-M6 are individually controlled by a speed control console CC and enable the operators to select the speed of each stand.

The automatic control system for adjusting the mill to maintain the thickness of the strip leaving stand F6 within tolerance preferably consists of a detector 23 as described in British patent specification No. 713,105 for measuring the departure of the thickness from the required value. The electrical signal representing that departure is applied, as illustrated, to the screwdown control circuit C6 of stand F6 to alter the draft at stand F6 in order to maintain the departure substantially zero and to the coiler 24. It will be appreciated that similar control circuits may be applied, if necessary, to other stands of the train 14.

The computing circuit 21 is, as shown in FIGURE 2, an analogue computer designed to solve the following equation:

AS is the change of screwdown setting B is the nominal width AB is the deviation of the width B from the nominal width B AT is the deviation of the bar temperature T from the nominal temperature T AH is the deviation of the bar thickness H from the nominal thickness H and a a a a 11 are suitable constants which may include dimensions.

The values for B T and H, are set in by the operators on dials 26, 27, 28 respectively, the values of AB, T and H are set in by the width meter 17, the pyrometer 16 and the thickness detector 18, respectively, and the output thickness representing the change in screwdown setting appears on the output line 30. The output of the pyrometer 16 on line 31 is applied to an amplifier 32 and the amplifier output is applied to a motor 33 which drives the slider 34 of a potentiometer 35 connected across a source of constant voltage. The voltage on slider 34 is applied to the input of amplifier 32 in opposition to the pyrometer output on line 31, so that the motor 33 takes up a position linearly related to the output on line 31. The width meter 17 is as described in British specification No. 795,525 and the nominal width setting dial 26 operate the setting shafts 50, 51 of FIGURE 4 of that specification; the departure of the detected bar width from that nominal value appears as the angular position of the shaft of motor 48 shown in FIGURE 3 of that specification. That shaft is coupled, either directly or through a remote control device to the slider of a potentiometer 36 of FIGURE 2 of the accompanying drawings. The nominal width setting dial 26 is coupled to the sliders of Potentiometers 37, 38, 40, 41 of the computing circuit. Similarly, nominal temperature and thickness setting dials 27, 28 are coupled to the sliders of potentiometers 42, 43 respectively, while pyrometer motor 33 drives the slider of 4 potentiometer 44 and the store 20 of thickness detector 18 drives the slider of potentiometer 45.

Considering now the computing circuit in detail, the slider of potentiometer 42 is connected to a resistor R1, potentiometer 37 and resistor R2 in series to the positive potential line. The slider of potentiometer 37 is connected through an adjustable resistor R3 to output line 30. Similarly, the slider of potentiometer 44 is connected through resistor R4, potentiometer 38 and resistor R5 to the negative potential line and the slider of potentiometer 38 is connected through resistor R6 to line 36. These two circuits together form the factor a (B +a )AT of the equation above. The slider of potentiometer 36 is connected through adjustable resistor R7 to line 30 and ntroduces the factor a A B of the above equation. The slider of potentiometer 43 which is set according to the nominal bar thickness, is connected through potentiometer 4t) and resistor R10 to the positive potential line and the slider of potentiometer 40 is connected through an adjustable resistor R8 to output line 30. Similarly, the slider of potentiometer 45 is connected through potentiometer 41 and resistor R11 to the negative potential line and the slider of potentiometer 41 is connected through adjustable resistor R9 to the output line 30. The last two circuits introduce the factor a ,(a -B )AH of the equation, so that the current in line 30 represents AS.

The output line 30 of the computer 21 is applied to the input of an amplifier 47 which controls a motor 48. The rotor of motor 48 is coupled to a selsyn 50 used as an induction regulator. The output winding 51 of selsyn 50 is connected across an auto-transformer 52 and across a phase-conscious rectifier 53. The output from rectifier 53 is applied to the input of amplifier 47 in opposition to the signal on line 30, so that the voltage applied across auto-transformer 52 is linearly related to the output from the computing circuit. Tapping lines L1-L6 are taken off the auto-transformer 52 and are connected to the control circuits C1-C6 for the respective stands F1-F6.

The control circuit for the screwdown on stand F6 is illustrated in FIGURE 3. The screwdown motor 54 drives the screws, as shown diagrammatically at 55, of the stand F6 through gearbox 56. Motor 54 is energised by a generator 57 the armature of which is supplied by a magnetic amplifier 58. The rotor of motor 54 is also coupled to the slider 60 of a potentiometer 61 connected acros a source of constant voltage.

The screw setting is adjusted by the operator by means of a dial 63 coupled to the rotor of a synchro transmitter having a stator winding 65. Winding 65 is connected to a differential synchro 66, the rotor of which is coupled to a dial 67, while the stator winding is connected to a synchro receiver 68. The output from synchro receiver 68 is applied through a resistor 70 to the input of amplifier 58 in opposition to the voltage on the slider 60 of potentiometer 61. By virtue of the feedback from motor 54 and potentiometer 61, the motor 54 is caused to take up an angular position linearly related to the input signal to amplifier 58 from synchro receiver 68.

The screwdown adjustment signal for stand F6, appearing across lines L, L6 (FIGURE 2) is applied through a switch S to the primary winding of a transformer '71, the secondary winding of which is connected across the resistor 70. A centre zero, phase-conscious, voltmeter '72 is connected across the primary winding of transformer 71 so as to give an indication to the operators of the adjustment of screwdown setting applied by the computing circuit. In its other position, switch S conmeets the thickness error detector 23 to the primary winding of transformer '71; switch S may be operated automatically to change over from the position shown when the bar enters the finishing train 14 and to change back again when the bar leaves, so as to prepare the circuit in readiness for the arrival of the next bar.

The roll speeds of stands Fl-F6 are adjusted by the operators by control console CC through the control circuits Mil-Mn in known manner. The roll speed computing circuit 19, which as described automatically changes the roll speeds from the values initially selected by the operators, should changes in the width, thickness or temperature of the bar as measured depart from the nominal values, is also an analogue computing circuit and is similar to the circuit 21 as shown in FIGURE 2.

The operation of the control system Will now be described:

After the initial setting up of the mill after a general rollchange, the operators incrementally alter the screwdown settings and roll speeds of the stands Fi-F6 for each bar to enter the finishing train from the values for the preceding bar, should the thickness and width required of the strip depart from those of the last strip to be rolled. In selecting the changes in the screwdown settings and roll speeds, the operators assume that the next bar will have the width and thickness appropriate for the next strip to be rolled and the bar will have the required temperature on the delay table, and the assumed values of Width, thickness and temperature are set on the dials 26, 27, 2 8 respectively. To adjust the screwdown on stand F6, for example, the dial 63 is operated until the required setting appears on an indicator '73 coupled to the dial. At the same time, the synchro rotor 64 is turned by dial $3 to produce an error signal at the output synchro 68. This error signal is applied to amplifier 58 and the screws are turned by motor 54 until the voltage from potentiometer 61 is equal and opposite to the voltage from synchro 6i and there is no resulting input to amplifier 58.

If the measured values of the Width and thickness and temperature of the bar on the delay table depart from those values set on dials 26, 27 and 28 respectively, a signal appears from the computing circuit 21 on the output line iii to produce a voltage across the auto-trans former 52 (FIGURE 2); the auto-transformer 52 in turn applies voltages to the lines Lil-L6 and, in the case of stand F6, a voltage appears across the primary winding of transfromer '71 and hence across the resistor 70. The voltage across resistor 7t? appears as an input to amplifier 58, causing the motor 54 to be operated and the screws 55 to be adjusted until the voltage from potentiometer 61 alters sufficiently to compensate the voltages both from transformer '71 and synchro 68. The amount of the screwdown adjustment is indicated on the indicator 72.

The tappings on auto-transformer 52 are selected to give the required ratio between the magnitudes of the adjustments made to the stands I i-F6. This ratio is chosen to give the best shape to the strip and for this urpose it is preferred to use a ratio 2.25 :2.0:l.'75 :l.5 1.25:1 for the adjustments made to stands F1, F2, F3, F4, F5, F6 respectively. However other ratios are possible; thus, equal adjustments may be made to each stand, or a geometrically progressing ratio such as 3.05 22.45 1.95:1.56: 1.25:1 may be used.

In similar manner, the roll speeds of stands Fl-Fd are altered automatically by the computing circuit 19, through the control circuits Mil-M6, to give roll speeds appropriate to the measured bar width, thickness and temperature.

When the bar has entered the finishing train 14, switch S is changed over and the thickness detector 23 becomes effective to control stand F6 in order to maintain the outgoing thickness within the required tolerance. When the bar has been rolled in the finishing train, the signals on lines 22 and P are removed so that the screwdowns and roll speeds of the stands Fl-Ffi return to the values selected by the operators before the entry of the bar to the finishing train. The circuit is then ready to measure and adjust the stands appropriately for the neX't bar, assuming the same output strip dimensions are required. No control by the operators is thus required, while successive bars are being rolled down to the same strip dimensions. When strip is required to be rolled to different dimensions, the operators must incrementally alter the screWdoWns and roll speeds and change the nominal width dial 26.

Between the rolling of successive bars in the finishing train 14, or preferably at longer intervals, the differential synchro 66 is adjusted by the dial 67 to reset the zero of the system and to take into account changes in the diameter of the rolls of stand F6.

Although the computing circuit 21 has been shown in FIGURE 2. as having provision for producing an error signal on line 30 when the thickness of the leading end of the bar departs from the assumed thickness, errors produced by variations in the thickness of bars on the delay table are of secondary importance, compared with those produced by variations in temperature and width. The potentiometens. 4G,. 41, 4-3 and 54, together with the thickness detector 18 and store 20 may thus in some circumstances be omitted, errors in the thickness of strip leaving stand F6 resulting from deviations in the bar thickness from the assumed value being corrected automatically by the automatic control system incorporating the strip thickness detector 23. The circuit 21 does not make provision for changes in the required outgoing thickness of the strip from the finishing train 14, since the latter are also liable to result in only small errors in the screwdown adjustment signals applied on lines Ll-Lfi and, in any event, the small resulting errors in trip thickness will be detected and compensated by the automatic control system incorporating the thickness detector 23.

Where, however, the required strip thickness departs considerably from the norm, the adjustable resistors R2, R3, R5, R6, R7, R8, R9, R10 and R11 are altered accordingly.

The other parameter of the bar which should be taken into account in setting up the mill is the material of the bar itself. The resistors R2, R3, R5, R6, R7, R8, R9, Rlt) and R11 determine the constants a a a a a of the equation solved by the computing circuit and, when a new material is being rolled, those resistances are altered appropriately.

The pyrometer 15 gives a voltage which is not linearly related to the detected temperature of the bar. However, the voltage. applied through resistor R6 to output line 30 is linearly related tothe temperature, because the resistors R4, R5. connected in parallel with potentiometer 4'4 appropriately changes the voltage/temperature characteristic to a straight line relationship over the efiective Working range; for this purpose, the resistance of resistors R4, R5 and potentiometer 38 is about 63% of the total resistance of potentiometer 44.

In accordance with the provisions of the patent statutes, we have explained the principle and operation of our invention and have illustrated and described what we consider to represent the best embodiment thereof.

However, we desire to have it under-stood that Within the scope of the appended claims, the invention may be practiced other-wise than as specifically illustrated and described.

We claim:

1. For a rolling mill having a plurality of stands, manually operable setting mean for each said stand effective to control the roll separation of that stand, and a delay table for receiving the metal to be rolled prior to entry thereof to the first said stand; a control system for setting up said stands prior to entry of said metal to the first said tand comprising means located adjacent said delay table and responsive to the width of said metal, means also located adjacent said delay table and responsive to the temperature of said metal, means responsive to the said computing circuit giving an output signal according to the departures of said width, temperature and thickness from said assumed values, and means controlled by said output signal for altering the roll separations of said stands in dependence on said departures.

2. An automatic control system as claimed in claim 1 in which said computing circuit includes an analogue computing circuit having inputs from said width, temperature and thickness responsive means and settable by said means settable to assumed values, said computing circuit giving an output substantially equal to B is said assumed value of width,

AB is the departure of width from B AT i the departure of temperature from said assumed value of temperature,

AH is the departure of thickness from said assumed value of thickness, and

a a a a and a are suitable constants.

3. An automatic control system according to claim 1 comprising also a transformer to which said output signal is applied and which has tappings for deriving control signals for automatically altering the roll settings of the various stands.

4. An automatic control system according to claim 3 in which the manually operable means for each stand comprise a remote position control system settable by the operator and controlling the roll setting of each stand, and in which the control signal from the transformed is injected into that position control system.

5. For a rolling mill having a plurality of stands, manually operable setting means for each said stand effective to control the roll separation of that stand, and a delay table for receiving the metal to be rolled prior to entry thereof to the first said stand; a control system for setting up said stands prior to entry of said metal to the first said stand comprising means located adjacent said delay table and responsive to the width of said metal, means also located adjacent said delay table and responsive to the temperature of said metal, means manually settable to assumed values of width and temperature, a computing circuit controlled by said width and temperature responsive means and by said means settable to said assumed values, said computing circuit giving an output signal according to the departure of said width and temperature from said assumed values, and means controlled by said output signal for altering the roll separations of said stands in dependence on the departures of the width and temperature from said assumed values.

6. An automatic control system according to claim 5 comprising also switch means operable to render said computing circuit ineffective to adjust the stands, when said metal enters the finishing train.

7. An automatic control system as claimed in claim 5 in which said computing circuit includes an analogue computing circuit for adjusting the roll separations of said stands and having inputs from said width and temperature responsive mean and settable by said means settable to assumed values, said computing circuit giving an output signal substantially equal to B is said assumed value of width,

AB is the departure of said width from B AT is the departure of said temperature from said assumed value of tempera-ture, and

a a and a are suitable constants.

8. An automatic control system as claimed in claim 5 also comprising means responsive to the thickness of the metal leaving the mill and means controlled by the last said means and effective to vary the roll separation of 8 at least the last stand of said mill to maintain the thickness substantially at a required value.

9. For a multi-stand finishing train of a rolling mill having a delay table for the reception of bars prior to entry to the first stand of said train, a control system for setting up the finishing train prior to entry of a bar, comprising a remote position control system for each stand having manually operable setting means and effective to control the roll separation of the stand according to the setting of said manually operable means; a width meter located adjacent the delay table and giving a first electrical signal in accordance with the width of the leading end of the bar on said delay table; a pyrometer located adjacent said delay table and giving a second electrical signal in accordance with the temperature of the leading end of said bar on said delay table; a computing circuit; means for applying said first and second signals to said computing circuit; means settable to assumed values of width and temperature; said computing circuit giving an electrical output signal according to the departure of said width and temperature from said assumed values; a distribution circuit, to which said output signal is applied, for deriving control signals in a prescribed ratio for said stands, and means for injecting said control signals into said remote position control systems, whereby said roll separations are altered in dependence on the departure of the width and temperature from said assumed values.

10. For a multi-stand finishing train of a rolling mill having a delay table for the reception of bars prior to entry to the first stand of said train, a control system for setting up the finishing train prior to entry of a bar, comprising a remote position control system for each stand having manually operable setting means and effective to control the roll separation of the stand according to the setting of said manually operable means; a width meter located adjacent the delay table and giving a first electrical signal in accordance with the Width of the leading end of the bar on said delay table; a pyrometer located adjacent said delay table and giving a second electrical signal in accordance with the temperature of the leading end of said bar on said delay table; a bar thickness measuring device giving a third electrical signal in accordance with the thickness of the leading end of said bar; a computing circuit; means for applying said first, second and third signals to said computing circuit; means settable to assumed values of width, temperature and thickness; said computing circuit giving an electrical output signal according to the departure of said width, temperature and thickness from said assumed values; a distribution circuit, to which said output signal is applied, for deriving control signals in a prescribed ratio for said stands, and means for injecting said control signals into said remote position control system, whereby said roll separations are altered in dependence on the departure of the width, temperature and thickness from said assumed values.

11. For a multi-stand finishing train of a rolling mill having a delay table for the reception of bars prior to entry to the first stand of said train, a control system for setting up the finishing train prior to entry of a bar, comprising a remote position control system for each stand having manually operable setting means and effective to control the roll separation of the stand according to the setting of said manually operable means; manually operable means for selecting the roll speed at each said stand; a width meter located adjacent the delay table and giving a first electrical signal in accordance with the width of the leading end of the bar on said delay table; a pyrometer located adjacent said delay table and giving a second electrical signal in accordance with the temperature of the leading end of said bar on said delay table; a first computing circuit; a second computing circuit, means for applying said first and second signals to both said computing circuits; means settable to assumed values of width and temperature; said computing circuits giving electrical output signals according to the departure of said width and temperature from said assumed values; a distribution circuit, to which said output signal from said first computing circuit is applied for deriving control signals in a prescribed ratio for said stands; means for injecting said control signals into said remote position control systems, whereby said roll separations are altered in dependence on the departure of the width and temperature from said assumed values; and means for applying said output signals of said second computing circuit to said roll speed selecting means, whereby said roll speeds are altered in dependence on the-departure of the width and temperature from said assumed values.

12. An automatic control system for a multi-stand rolling mill comprising means for independently adjusting the roll separation and roll speed of each of the stands of the mill, means for measuring automatically the width and temperature of the leading end of the bar immediately prior to entry thereof to the mill, a computing circuit which is responsive to the measuring means and which includes means connected to said adjusting means for effecting an adjustment of the roll separations and roll speeds of the stands of the mill.

13. For a rolling mill having a plurality of stands, means for adjusting the roll separation of each said stand, and a delay table on which the metal is located prior to entry to the first said stand; a control system comprising means responsive to the temperature of said metal on said delay table, means responsive to the width of said metal on said delay table, computing means controlled by said temperature responsive means and said width responsive means, and means controlled by said computing means for automatically operating said roll separation adjustment means of at least one of said stands.

14. For a rolling mill having a plurality of stands, means for individually adjusting the roll separation of each said stand, and a delay table for receiving the bar prior to entry to the first said stand; a control system comprising means responsive to the temperature of the bar on said delay table, means responsive to the width of said bar on saiddelay table, means responsive to the thickness of said bar on said delay table, computing means controlled jointly by said temperature, width and thickness responsive means, and means controlled by said computing means for automatically operating said roll separation adjusting means of at least one of said stands.

15. For a rolling mill having a plurality of stands, means for individually adjusting the roll speed of each said stand, means for individually adjusting the roll separation of each stand, and a delay table for receiving the bar prior to entry to the first said stand; a control system comprising means responsive to the temperature of the bar on said delay table, means responsive to the Width of said bar on said delay table, computing means controlled jointly by said temperature and width responsive means, and means controlled by said computing means for automatically operating said roll separation adjusting means and said roll speed adjusting means.

16. For a rolling mill havign a plurality of stands, means for individually adjusting the roll speed of each said stand, means for individually adjusting the roll sep aration of each said stand, and a delay table for receiving the bar prior to entry to the first said stand; a control system comprising means responsive to the temperature of the bar on said delay table, means responsive to the width of said bar on said delay table, means responsive to the thickness of said bar on said delay table, computing means controlled jointly by said temperature, width and thickness responsive means, and means controlled by said computing means for automatically operating said roll separation adjusting means and said roll speed adjusting means.

17. For a rolling mill having a plurality of stands, means for individually adjusting the roll separation of each said stand, and a delay table for reciving the bar prior to entry to the first said stand; a control system comprising means responsive to the temperature of the bar on said delay table, means responsive to the width of said bar on said delay table, computing means controlled jointly by said temperature and width responsive means, and means controlled by said computing means and eflective prior to entry of the bar to the first stand for automatically operating said roll separation adjusting means.

18. For a rolling mill having a plurality of stands, means for individually adjusting the roll speed of each said stand, means for individually adjusting the roll separation of each said stand, and a delay table for receiving the bar prior to entry to the first said stand; a control system comprising means responsive to the temperature of the bar on said delay table, means responsive to the width of said bar on said delay table, means responsive to the thickness of said bar on said delay table, computing means controlled jointly by said temperature, width and thickness responsive means, and means controlled by said computing means and effective prior to the entry of said bar to the first said stand for automatically operating said roll separation adjusting means and said roll speed adjusting means.

19. A control system for a multi-stand rolling mill comprising:

(a) a plurality of roll stands; each including a pair of rolls;

(b) an electric motor arranged to vary the spacing of one pair of rolls;

(0) manually settable means by which the control system can be set to handle a piece of material having certain assumed characteristics;

(d) first measuring means responsive to the Width, temperature, and thickness of the piece of material;

(e) second measuring means responsive to an output parameter of the piece of material; and

(f) circuit means by which the manually settable means, the first measuring means and the second measuring means are linked to the electric motor and so arranged that the setting efiected by the manually settable means is automatically varied by the first measuring means until the piece of material is passing between the rolls and the setting is then varied by the second measuring means.

References Cited by the Examiner UNITED STATES PATENTS OTHER REFERENCES Control Engineering, September 1956, pages 116, 117. Electronics, October 21, 1960, pages 65-67. Electronics, October 28, 1960, pages 32, 33.

WILLIAM J. STEPHENSON, Primary Examiner.

LEON PEAR, CHARLES W. LANHAM, MICHAEL V. BRINDISI, Examiners. 

1. FOR A ROLLING MILL HAVING A PLURALITY OF STANDS, MANUALLY OPERABLE SETTING MEANS FOR EACH SAID STRAND EFFECTIVE TO CONTROL THE ROLL SEPARATION OF THAT STAND, AND A DELAY TABLE FOR RECEIVING THE METAL TO BE ROLLED PRIOR TO ENTRY THEREOF TO THE FIRST SAID STAND; A CONTROL SYSTEM FOR SETTING UP SAID STANDS PRIOR TO ENTRY OF SAID METAL TO THE FIRST SAID STAND COMPRISING MEANS LOCATED ADJACENT SAID DELAY TABLE AND RESPONSIVE TO THE WIDTH OF SAID METAL, MEANS ALSO LOCATED ADJACENT SAID DELAY TABLE AND RESPONSIVE TO THE TEMPERATURE OF SAID METAL, MEANS RESPONSIVE TO THE THICKNESS OF SAID METAL ON SAID DELAY TABLE, MEANS MANUALLY SETTABLE TO ASSUMED VALUES OF WIDTH, TEMPERATURE AND THICKNESS OF SAID METAL, A COMPUTING CIRCUIT CONTROLLED BY SAID WIDTH, TEMPERATURE AND THICKNESS RESPONSIVE MEANS AND BY SAID MEANS SETTABLE TO SAID ASSUMED VALUES, SAID COMPUTING CIRCUIT GIVING AN OUTPUT SIGNAL ACCORDING TO THE DEPARTURES OF SAID WIDTH, TEMPERATURE AND THICKNESS FROM SAID ASSUMED VALUES, AND MEANS CONTROLLED BY SAID OUTPUT SIGNAL FOR ALTERING THE ROLL SEPARATIONS OF SAID STANDS IN DEPENDANCE ON SAID DEPARTURES. 